This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The human oral biofilm, dental plaque, is a well-recognized example of a multi-species bacterial community. My research interest lies in the study of communication between different species of bacteria that compose dental plaque. This communication includes cell-cell contact and metabolic interactions between organisms in the biofilm. My current research focus is communication that occurs between two members of the plaque community, Veillonella atypica and Streptococcus gordonii. When these organisms are growing together, S. gordonii induces expression of an alpha-amylase gene that is not expressed when S. gordonii is grown without V. atypica. My goals are to identify the mechanism of signaling that occurs between these species and determine the importance of amylase expression to development of the mixed-species community. We have recently identified a gene that may play a role in the ability of S. gordonii to induce amylase expression in response to V. atypica. As a first step in understanding the molecular basis for the signalling between S. gordonii and V. atypica, we constructed a strain carrying a mutation in this gene. Current work is aimed at characterizing the mutant with respect to its ability to respond to V. atypica.